Combined Heat and Power Plant Generation
Introduction
TAVANA Co. is trying to support the growth of CHP capacity in Iran and to enable the CHP industry to meet the challenges ahead.
Combined Heat and Power (CHP), the simultaneous generation of heat and power, is a highly efficient way to use both fossil and renewable fuels. CHP can therefore make a significant contribution to Iran's sustainable energy goals, bringing environmental, economic, social and energy security benefits.
CHP is already making a valuable contribution towards these goals, particularly the reduction of carbon emissions. However, in recent years the CHP industry has faced serious economic difficulties. CHP has the potential to make further significant contributions to the security, diversity and competitiveness of energy supply and to help support a competitive manufacturing industry for sustainable energy technologies in Iran.
What is CHP?
1- Combined Heat and Power (CHP) is a highly fuel-efficient energy technology, which puts to use waste heat produced as a by-product of the electricity generation process. CHP can increase the overall efficiency of fuel utilization to more than 75% Gross Calorific Value – compared with around 40% achieved by fossil fuel electricity generation plants in operation today, and up to 50% from modern Combined Cycle Gas Turbines – and has the potential to save substantially on energy bills.
2- CHP is the simultaneous generation of usable heat and power (usually electricity) in a single process. Most new CHP schemes use natural gas, but a significant proportion burn alternative, renewable fuels and some, such as those bio-fuels that are suitable for use, qualify for additional support (e.g. under the Renewable Obligation).
3- CHP is not only more efficient through utilization of heat, but it also avoids transmission and distribution losses and can provide important network services such as “black start”, improvements to power quality, and the ability to operate in “island mode” if the distribution network goes down.
4- The possibility of linking heat users together, including community heating to link up residential users, can provide additional opportunities for the commercial exploitation of CHP. Community heating involves the use of appropriate centralized heat sources for heating of a number of separate premises. Community heating has already proved effective in dense city developments and residential developments, shopping centres and business parks.
5- Table 1 contains a classification of CHP schemes by size. CHP has traditionally been deployed in larger applications involving CHP schemes of several hundred kWe and above. The replacement of domestic boilers with micro-CHP units, which can generate electricity (around 1–5 kWe) as well as heat for space heating, may offer further potential for energy savings. However, significant market penetration is not expected over the short term. Larger micro-CHP and mini-CHP have potential in the small business sector, such as retail, catering, guesthouses and nursing homes. In aggregate, they may therefore make a significant contribution to future installed CHP capacity. A number of issues are yet to be resolved and, at this stage, it is uncertain how much micro-CHP will contribute to the 2010 target.
Summary of CHP Technologies:
1- Gas Turbine
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Advantages: High reliability, Low emissions, High grade heat available and No cooling required.
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Disadvantages: Require high pressure gas or in-house gas compressor, Poor efficiency at low loading and Output falls as ambient as temperature rises.
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Available Sizes: 500 kW to 40 MW.
2- Micro Turbine
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Advantages: Small number of moving parts, Compact size and light weight, Low emissions and No cooling required.
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Disadvantages: High costs, Relatively low mechanical efficiency and Limited to lower temperature cogeneration applications.
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Available Sizes: 30 kW to 350 kW.
3- Spark Ignition (SI) Reciprocating Engine or Diesel/ Compression Ignition (CI) Reciprocating Engine
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Advantages: High power efficiency with part load operational flexibility, Fast start-up, Relatively low investment cost, Can be used in island mode and have good load following capability, Can be overhauled on site with normal operators and Operate on low-pressure gas.
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Disadvantages: High maintenance costs, Limited to lower temperature cogeneration applications, Relatively high air emissions, Must be cooled even if recovered heat is not used and High levels of low frequency noise.
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Available Sizes: < 5 MW, High speed (1,200 RPM) ≤4MW and Low speed (60-275RPM) ≤65MW.
4- Steam Turbine
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Advantages: High overall efficiency, Any type of fuel may be used, Ability to meet more than one site heat grade requirement, Long working life and high reliability and Power to heat ratio can be varied.
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Disadvantages: Slow start up and Low power to heat ratio.
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Available Sizes: 50 kW to 250 MW.
5- Fuel Cells
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Advantages: Low emissions and low noise, High efficiency over load range and Modular design.
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Disadvantages: High costs, Low durability and power density and Fuels requiring processing unless pure hydrogen is used.
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Available Sizes: 200 kW to 250 kW
The CHP System has the following benefits:
1- Energy savings – If energy for power, heating or cooling is a big component of your costs, your energy savings will be proportionately large. Savings can lead to a quick payback on CHP systems investments when combined with tax credits, excess energy sales and cogeneration gas discounts offered by some utilities.
2- High reliability – Generating power and heat on-site, and using the power grid or a standby power system for backup, will improve reliability and maintain productivity.
3- Cleaner air – By reducing your
dependence on inefficient centralized power plants, you
reduce the amount of air pollution those plants produce. New diesel engine
generators, lean-burn gas engine generators and micro turbines are all cleaner
than ever before, that means reduced levels of nitrogen oxides, sulfur dioxide,
particulates and greenhouse gases such as carbon dioxide.
4- Easy installation and expansion – Scalable systems from 30 kW to 30 MW can typically be installed faster than a utility can build a comparable high-voltage substation. And the system can easily be expanded as your facility grows.
5- Good for the future – Since cogeneration significantly reduces energy waste, it preserves our coal, oil and nuclear resources for future generations.
Examples of industry utilizing the CHP technology:■ Ammonia/fertilizer plants
■ Incineration plants
■ Chemical plants
■ Pharmaceutical plants
■ Pulp, Paper & Textile
■ Sugar/food
■ Power and desalination
■ District heating
■ Universities/hospitals
The CHP systems can be economically attractive for many types of buildings, including, but not limited to the following:
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Hospitals
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Greenhouses
- Hotels
- Industrial/chemical plants
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Textile Plants
- Government facilities
- Colleges and Universities
- Food processing
- Health clubs
- Swimming pools
- Nursing homes
- District heating
- Coal mining and oil fields
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Absorption Chillers and Boilers
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Landfills and much more